Phenyl acetaldehyde compounds as regulators for the polymerization of unsaturated polyester resins with ethylenically unsaturated monomers



Jan. 4, 1966 Filed March 19, 1962 H. HOPFF ETAL 3,227,779 PHENYL ACETALDEHYDE COMPOUNDS AS REGULATORS FOR THE POLYMERIZATION OF UNSATURATED POLYESTER RESINS WITH ETHYLENICALLY UNSATURATED MONOMERS 2 Sheets-Sheet l I I l I ZgJ- l l I I INVENTORS HNE? BY )M ATTORN 5 Jan. 4, 1966 H. HOPFF ETAL 3,227,779

PHENYL ACETALDEHYDE COMPOUNDS AS REGULATORS FOR THE POLYMERIZATION OF UNSATURATED POLYESTER RESINS WITH ETHYLENICALLY UNSATURATED MONOMERS ATTORNEYS United States Patent O 3,227,779 PHENYL ACETALDEHYDE COMPOUNDS AS REG- ULATORS FOR THE POLYMERZATION F UN- SATURATED POLYESTER RESENS WITH ETHYL- ENICALLY UNSATURATED MONOMERS Heinrich Hopl and Eduard Kleiner, Zurich, Switzerland, assignors to Deutsche Goldund Silber-Scheideanstalt vormals Roessler, Frankfurt am Main, Germany Filed Mar. 19, 1962, Ser. No. 182,705 Claims priority, application Germany, July 15, 1960, D 33,789; Mar. 18, 1961, D 35,690 11 Claims. (Cl. 26d- 861) This application is a continuation-in-part of application Serial No. 123,544, tiled July 12, 1961 now abancloned.

The present invention relates to an improved process for regulating the copolymerization of unsaturated polyester resins with ethylenically unsaturated monomers with the aid of phenyl acetaldehydes as polymerization regulators.

It is known that unsaturated polyesters derived from unsaturated dicarboxylic acids, such as maleic acid, itaconic acid, fumarie acid and the like, with glycols can be converted to cross-linked polymers by copolymerization with monomeric ethylenically unsaturated compounds such as styrene, acrylic esters, for example, methyl methacrylate, methyl acrylate, diallyl phthalate, triallyl cyanurate and the like, with the aid of peroxidic catalysts, such as benzoyl peroxide, cumene hydroperoxide, cyclohexyl hydroperoxide and the like. Copolymers of this type have found many technical uses, especially in combination with glass bers. ln general, they possess good mechanical properties but they do not fulfill all requirements with reference to impact strength.

The term polymerization regulators is employed herein to signify such compounds which steer the copolymerization in a different manner and way than the previously employed peroxides, for example, benzoyl peroxide. The difference in the manner the copolymerization is steered or regulated is most conspicuously noticeable in the properties of the copolymer products. inent property of the new polymerization regulators is the accelerating action thereof. Other valuable properties of the novel polymerization accelerators will become evident from the following.

The copolymerization according to the invention is effected between unsaturated polyester resins and liquid polymerizable monomers containing one or more terminal CH2=C groups. Such polymerizable monomers, for instance, are vinyl esters, such as vinyl acetate, vinyl propionate, vinyl ethers, such as vinyl methyl ether, acrylic and methacrylic acid esters, such as their methyl, ethyl and butyl esters, acrylonitrile, butadiene, 2-chlorobutadiene, diallyl maleate and especially aromatic vinyl compounds, such as styrene. The aromatic aldehydes employed according to the invention are particularly effective in steering and accelerating the copolymerization of unsaturated polyesters with styrene and substituted styrenes, such as vinyl toluenes and vinyl ethyl benzenes, as the monomer and simultaneously as the solvent.

The polyester resins which can be copolymerized according to the invention with the ethylenically unsaturated monomers can be all polymerizable unsaturated polyesters derived from dibasic carboxylic acids and polyhydric alcohols, at least one of the carboxylic acid or polyhydric alcohol components being unsaturated. Examples of dicarboxylic acids which can serve as the acid components of the polyesters, for example, are succinic acid, adipic acid, terephthalic acid, phthalic acid, as well as the unsaturated dicarboxylic acids, maleic acid, itaconic acid, fumarie acid, tricarballyl acid and the like.

Evidently the promice The alcoholic components of the polyesters can include glycol, ethylene glycol, diand triethylene glycol, trimethylene glycol, hexamethylene glycol, allyl alcohol, 2-butene-l,4 diol and the like. Of course, it is to be understood that such polyesters can be produced from the corresponding acid anhydrides, such as maleic anhydride, instead of the acids or corresponding mixed esters or ester mixtures.

The polymerization regulators according to the invention are phenyl acetaldehyde compounds of the following general formula Ar H CH-C R O wherein Ar is phenyl or substituted phenyl group such as alkyl, alkyloxy and halogen substituted phenyl groups and R is hydrogen, alkyl or phenyl.

Examples of such compounds are phenyl acetaldehyde, p-rnethyl phenyl acetaldehyde, p-ethyl phenyl acetaldehyde, mand p-chlorophenyl acetaldehyde, the a-methyl, ethyl or phenyl substituted phenyl acetaldehydes, especially hydratropaldehyde and diphenyl acetaldehyde. ln contrast to the above phenyl acetaldehyde compounds which still retain l or 2 hydrogen atoms on the a carbon atoms, those not containing a hydrogen atom on the a carbon atom, such as in triphenyl acetaldehyde, or 2,4-

diphenyl crotonaldehyde, that is, a phenyl acetaldehyde, the a carbon atom of which also carries the :CH-CHZ-CSHE substituent, are considerably less active. The activity of hydrocinnamic aldehyde as an accelerator is higher than that of the disubstituted phenyl acetaldehydes, such as triphenyl acetaldehyde. The accelerating action of hydratropaldehyde is greater than that of phenyl acetaldehyde and its substitution products in which the substituents are in the benzene nucleus.

The phenyl acetaldehyde regulating compounds according to the invention can be employed singly or in admixture with a peroxidic catalyst.

In the accompanying drawings:

FIG. 1 shows exotherm curves for copolymerization of a commercial unsaturated polyester resin with styrene mixture with various proportions of benzoyl peroxide and phenyl acetaldehyde at a bath temperature of 70 C.;

FIG. 2 shows exotherm curves for copolymerization of a commercial unsaturated polyester resin with styrene mixture with various proportions of benzoyl peroxide and phenyl acetaldehyde at a bath temperature of C.;

FIG. 3 shows exotherm curves for copolymerization of a commercial polyester with styrene mixture with various proportions of phenyl acetaldehyde at a bath temperature of C.;

FIG. 4 shows gel time curves for copolymerization of a commercial polyester resin with styrene mixture as a function of temperature and catalyst with phenyl acetaldehyde and benzoyl peroxide;

FIG. 5 shows gel time curves for copolymerization of a polyester resin With styrene as a function of quinone and hydroquinone as retarders with hydratropaldehyde and benzoyl peroxide as catalysts;

FIG. 6 shows exotherm curves for copolymerization of another polyester resin with styrene with various proportions of benzoyl peroxide and hydratropaldehyde at a bath temperature of 70 C.;

FIG. 7 shows exotherm curves for copolymerization of such other polyester resin with styrene with various proportions of benzoyl peroxide and hydratropalhedye at a bath temperature of 80 C.;

FIG. 8 shows exotherm curves for copolymerization of the same polyester resin as in FIGS. 1 5 with styrene with various phenyl acetaldehyde compounds as catalysts;

FIG. 9 shows exotherm curves for copolymerization of the same polyester as in FIGS. 1-5 with various propori The stabilized form increases the gel time required for the polyester-styrene solutions somewhat.

The following Table 1 shows progress of the copolymerization of the same polyester-styrene mixtures contions -of hydratropaldehyde; cerned in FIGS. 1-5 of the drawings with various quan- FIG. 10 shows a gel time curve for copolymerization of tities of distilled and stabilized phenyl acetaldehyde and the same polyester as in FIGS. 1-5 with styrene as a benzoyl peroxide as well as the aspect of the polymerizate function of various proportions of hydratropaldehyde; produced and the following Table 2 compares several FIG. 11 shows a heat temperature curve for the comechanical properties of the polymerizates thus obtained.

TABLE l Polymerization Progress Percent Bath Gel Peak Catalyst by wt. Temp., Time, Temp., Polymer C. Min. C.

2 70 1G 72 Water clear-crack free. 1 70 19.4 72 Do. 2 a s. S7 e@ 1 85.2 0 Phenylacetaldehyde distilled. 0- s". 80 1.0 5 85 D0- 0. so 1s. 5 84. 5 Do. 2 100 4 131. 5 Water clear-cracked. l 10() 5 123 Water clear-crack free. P1 l t 1d l 1 0.5 100 6. 25 11S Do.

llly 2.06 a e ly stabilized with S' 5 0 ionone 10. lo 0.

2 70 9. 5 173 Yellowish-crack free. 1 70 13. 5 153 Do.. BenzoyLpcroXide A Yellggish-cracked.

0.5 80 7.5 172 Do. 0.25 so 10.5 152 Do.

polymerization of the same polyester as in FIGS. 1-5 with styrene as a function of various proportions of hydratropaledehyde; and

FIG. 12 shows exotherm curves for copolymerization of the same polyester as in FIGS. 1-5 with styrene using hydratropaldehyde and benzoyl peroxide and mixtures thereof as catalysts.

The polyester upon which the curves in FIGS. 1-5 and 8-12 are based was prepared by heating a mixture of l mol of maleic acid anhydride, 1.6 mol of phthalic acid anhydride, 1.6 mol yof ethylene glycol and 1 mol of diethylene glycol until the acid number reached 25.7. The polyester styrene mixture used was prepared by mixing 500 parts of such polyester with 250 parts of freshly distilled styrene. The acid number of the mixture was 17.2.

The polyester upon which the curves in FIGS. y6 and 7 were obtained contains -maleic acid, orthophthalic acid and propylene glycol 1,2 in a molar proportion of 1:1:2. The polyester styrene mixture contained of styrene and also contained 0.01% of hydroquinone as a stablizer. Its acid number was 20.

As can be seen from FIGS. 1-3, v6, 7 and l2, the progress of the copolymerizati-on is fundamentally dierent when phenyl acetaldehyde compounds are used instead of benzoyl peroxide. With benzoyl peroxide the progress of the polymerization after gelation is almost explosive as can be seen from the steep temperature rise and high exotherm peak. In view of the large temperature diicrences within the polymerizate, cracked products are often obtained which in addition have a yellow cast and are brittle. When phenyl acetaldehyde compounds are used the polymerization of an unsaturated polyester styrene solution after gelation proceeds uniformly without temperature rises worth mentioning with the result that completely crack free products having a smooth surface are obtained which have a transparency and clarity comparable to those obtained with lpolymers of methacrylates. On the other hand, as can be seen from FIG. 4, the gel times of unsaturated polyester-styrene solutions catalysed with benzoyl peroxide and with phenyl acetaldehyde are very close to each other.

The phenyl acetaldehyde or its substitution products can he used in pure form or in iononc stabilized form.

TABLE 2 Mechanical properties Polymerized with 2% Pheuylacet- 2% Benzoylaldehyde peroxide Impact strength:

(a) based on the cross-section.. (b) based on the 6 fold n10- ment of resistance. Bending strength Bending angle upon break.

1750 11g/cm.2 18.2.

It will be seen from Table l that with phenyl acetaldehyde, products can be obtained at 70 to 100 C. which are water clear and crack free, whereas with benzoyl peroxide at C. cracked products are always produced. In the last instance also the peak exotherm temperature is about C. higher than when the phenyl acetaldehyde according to the invention is employed.

While the theoretical basis for the action of the phenyl acetaldehyde compounds employed according to the invention cannot be considered completely certain, it has been proved that the polymerization mechanism must be of radical nature.

Known inhibitors such as quinone and hydroquinone have an inhibiting or reaction retarding action upon copolymerizations carried out according to the invention. As can be seen from FIG. 5 in the drawings quinone has a stronger inhibiting effect than hydroquinone when hydratropaldehyde is used as the polymerization regulator. As also shown in such figure the inhibiting elect of quinone is stronger than that of hydroquinone in a peroxide catalysed copolymerization. The influence of these known reaction retarders in radical catalysis would seem to indicate that a radical controlled reaction mechanism must be involved with the regulators employed according to the invention.

The activity of various individual aldehydes is indicated in the following Table 3 using the polyester styrene mixture as in FIGS. 1-5. ln this and in the scceeding Tables the hardening time signiiies the time between the initiation of the polymerization and the point when the peak temperature is reached.

6 comparison with phenyl acetaldehyde it has a further advantage in that it does not undergo autopolymerization and therefore does not require special stabilization. The activity of diphenyl acetaldehyde can be compared with that of phenyl acetaldehyde and p-methylphenyl acetaldehyde.

TABLE 3 Quantity of resin g 2O Bath temperature C" 100 Test tube diameter mm- 20 Percent Gel Peak Hardening Regulator by Wt. Time, Temp., time, Miu.

Min. C.

Phenylacetaldehyde 2 4 131. 5 17 1 5 123 2O Hydratropaldehyde 2 3 139 11. 5

1 4 140 13 Diphenylaeetaldehyde 2 4. 5 127 11 1 5 114. 5 12 p-Methylphenylacetaldehyde 2 4. 5 131. 5 17 1 5 129. 5 20 p-Chlorophenylacetaldehyde 2 1 23. 5 108 40 p-Methoxyphenylaeetaldehyde 2 14. 5 113 2S 1 37. 5 112. 8 44 2.4.t5-trimethylphenylaeetaldehyde 2 14. 5 110` 25 1 32 106. 5 45 Ilydrocnnamiealdehyde 2 17 117 31 Although 80 C. is an optimum bath temperature for the production of a uniform polymerization, a bath temperature of 100 C. was employed for the tests tabulated in such table to save time while illustrating the different activities of the various aldehydes. Disregarding the fact that the manner in which the starting materials (precondensates) have been prepared, the mixing proportions and the state of the starting materials have a certain inuence on gel and hardening times and the peak temperatures, it can be ascertained from the values in such table that the concentration of the regulator employed has less inuence upon the gel and hardening times than on the peak temperatures.

ltropal-dehyde and benzoyl peroxide is illustrated in the following Tables 4 and 5.

TABLE 4 Polyestersame as used in FIGS. l-S in styrene Quantity of resin g 20 Test tube diameter mm 20 Bath temperature C 8O Catalyst or Regulator Percent Mol Gel time, Peak Hardening by wt. Min. Temp., C. time, Min.

Ilydratropaldehyde 2 0. 003 6. 0 94'. 5 22 l 0.0015 10 92 39 0. 5 0. 00075 20 89 36 Benzoylperoxrde 1. 8 0. 0015 5. 75 198 8. 5 H d t 1d I d l 0.9 [30075 7.5 194.5 10.5

y ra ropa e 1y e p us... 1 015 eroylpertidhe 0.9 0.00075 4 5 181 8 y aropa e yde plus. 1 0.00015 Benzoylperoxide 0.15 9'5 137 15'5 When diphenyl acetaldehyde and hydratropaldehyde are used as the regulators it was found that the maximum peak temperatures were reached in general at a concentration between 1 and 2% by weight whereas at lower Especially short gel and hardening times are obtained in the copolymerization of unsaturated polyester with methyl methacrylate or vinyl acetate as can be ascertained from the following Table 5.

TABLE 5 Same polyester as in FIGS. 1-5 mixed with vinyl acetate and methyl methacrylate.

Quantity of resin g 20 Test tube diameter mm-- 2O The polymerization temperatures can vary within wide limits. It is, however, expedient to employ temperatures above room vtemperature in order that polymerization times which are not too long are obtained. It is especially expedient also to effect the mixture of the react-ion partners, that is, Ithe compounds Vto be polymerized with the polymerization regulator, at elevated temperatures, for example, lbetween 30 and 120 C., preferably at about 50 to 80 C. It is, however, not necessary to employ elevated temperatures. When the length of time of hardening need not 1be Itaken into consideration the reaction partners can `also be mixed at temperature-s of about 30 to 40 C. and to start the copolymerization at such temperatures. The actual polymerization can be started at the same temperature or a temperature somewhat higher than the mixing temperature. The polymerization temperatures expediently are Ibetween 40 and 120 C., preferably between 60 and 100 C.

The phenyl acetaldehyde compounds according to the invention, particularly lthe hydratropaldehyde, are distinct- -ly superior to benzoyl peroxide at copolymerization temperatures between about 50 and 90 C. with regard to accelerating action and the quality and appearance of the copolymerized product. Some variations may occur with reference to the temperature range depending upon the type and source of the polyester employed.

The qua-ntity of phenyl acetaldehyde compounds employed according to the invention can be varied Within wide limits. However, it is useless to employ quantities greater than are necessary. For practical reasons therefore the upper limit is about by weight of the reaction mixture. In general, small quantities of over 0.1%, preferably between 0.5 to 3%, of the reaction mixture are `already suicient to efect com-plete curing (hardening) in short periods of time, for example, in about 3 to minutes at temperatures of 50 to 100 C.

As the presence of molecular oxygen is not detrimental to the polymerization, it does not have to be carried out in a closed vessel or underya protective gas, such as nitrogen. As no special protective measures are required and open molds may be used, the process according to the invention is especially adapted for general use. For example, it may be used in the dental field, such =as for the production of fillings, prostheses, artificial teeth and the like, or for the production of other shaped bodies. The shaped `bodies produced with the regulators according to the invention are water clear and free of cracks. In addition, iibers, filaments, foils, bands, plates or other shaped bodies may be produced therefrom by h-ot shaping procedures. Also, lillers, dyes, pigments, glass fibers or mineral wool can be added to the starting materials to effect coloration or improve the mechanical properties of the iinished products. Furthermore, when suitably prepared, the polymerizates obtained by the process according to the invention can be used for coating purposes or the starting materials can be used for so-called two component lacquers.

The following examples will serve to illustrate several embodiments of the invention.

Example 1 A polyester with an acid number 20 obtained by heating 6,25 mol of maleic acid anhydride, 3.75 mol of phthalic acid anhydride and 10 mol of diethylene glycol was mixed at 50 C. with 30% by weight off styrene and 0.5% by weight of phenyl acetaldehyde and then heated for minutes to 80 C. The gelation began after about 15 minutes and the temperature rose during the copolymerization to C. The polymerization product solidiiied after 60 minutes.

Example 2 parts by weight of a polyester obtained by heating l mol of maleic acid anhydride, 1.6 mol of -phthalic acid anhydride, 1.6 mol of ethylene glycol and 1 mol of diethylene glycol were mixed with 30 parts by weight of styrene and 1 part by weight of phenyl acetaldehyde at 50 C. and then heated to 80 C. The gelation began after 8.5 minutes and during the copolymerization the peak temperature was only 85 C. Complete curing was achieved after 60 minutes.

Example 3 The gel time, peak temperatures and curing time obtained with an analogous polyester-styrene mixture prepared according to Example 2 with various phenyl acetal- `dehyde compounds at a bath temperature of 100 C. with 20 g. batches in test tubes 20 mm. in diameter are given in the following Table 6:

9 l0 Example 4 TABLE 8 20 g. samples of a polyester styrene solution having an `acid number of 31 and containing 1 mol maleic acid per Regulator ,llzerlgu 409 g. polyester styrene solution (same polyester styrene C solution as concerned in FIGS. 6 and 7) were copolym- 5 erized in test tubes 20 mm. in diameter in oil baths main- 2% genylacetalgehye 4 131. 5 17 tained at 70 and 80 C. using 0.5, 1.0 and 2% by weight 22g HyggglggrlFggyYdeg gg ,12g of hydratropaldehyde. In comparison further samples gydatrolpaiieliyge 4?) were copolymerized using 0.5, 1.0 and 2% of benzoyl 1.75 Dghglgtldhgd:* 6 11M 12 peroxide. The course of the temperature in the polyml 2% p21/Iethylphenylacetaldehyde 4.5 131.5 17 erizing mixtures is given in FIGS. 6 and 7. As can be g igggglfgge 14.2 lz'l gg seen from such figures the peak temperatures reached 1% p-Methxyphenylacetaldhyde- 37.5 112.8 44 using hydratropaldehyde are up to 111.5 C. lower than n those reached with benzoyl peroxide. The course of the temperature during the polymeriza- The following table gives the gel times, peak temperaltion with diphenyl acetaldehyde 1s particularly noteitures, hardening Itimes, as well as the appearance of the Worthy 2S Wlh Short gel and harderllrlg lrrleS Peak lempolymerized products of the Various samples. peratures of only 127 C. and 114.5 C. were reached.

TABLE 7 Bath Gel Peak Hardening Catalyst or regulator Temp., Time, Temp., Time, Min. Appearance C. Min. C.

2% Hydratropaldehyde 70 6. 5 100. 5 25 Crack free, smooth surface. 1%Hydratropa1dehyde 70 22 90 40 D0. 0.5%Hydratropaldehyde. 70 45 S5 55 Do. 2% Benzoyl-peroxide- 70 l1. 75 212 13. 5 Strongly cracked, brittle. 1% Benzoyl-peroxide 70 17. 75 198 21. 25 Do. 0.5% Benzoyl-peroxide. 70 32 178 38 Crack free, rough surface. 2% Hydratropaldehyde 80 3.5 138 14 Crack free, smooth surface. 1% Hydratropaldehyde s0 13. 5 139 22.5 Do. 0.5% Hydratropaldehyd 80 22 115 33 Do. 2% Benzoylperoxide 80 5. 5 228 7 Strongly cracked, brittle. 1% Benzoylperoxide 80 7.75 218 10 Do. 0.5% Benzoylperoxide 80 11.5 210 14. 25 Do.

As can be seen from such table shorter gel times are w Example 6 Obtained With hydratropaldehyde ln quarlltles between "o g. samples of the same polyester styrene solution as l and r2% by Weight rllarl Wl'rll berlZ'oYl PeroXlde- Wlllle used in Example 5 were copolymerized in test tubes 20 all PolYmerlZaeS obtalrled Wl'fll hydratropaldehyde Were mrn. in diameter in an oil bath maintained at 100 C. Crack free and had-a Smooth Surface, all those oballed using quantities of hydratropaldehyde between 0.25 and With berlZoyl 'PeroXlde Wlth the eXePllO11 of the Sample 40 8% by weight. FIG. 9 shows the exotherin curves oberrlPlol/rlg 05% at a bath emperaure 0f 70 C- Were tained with the various samples. As can be seen, a maxi- Cracked brittle Prodllo3- EVeIl though the Poli/'merma' mum peak temperature is reached with quantities of the riorl Was Ilot Carried out Under Ultrogen, the Products regulator between 1 and 2% by weight. As has already Cured Completely eVerl at the Surfaoesbeen indicated, this is contrary to what occurs in polymerizations employing benzoyl peroxide as a catalyst in which the greater the quantity of peroxide used the higher the Example 5 peak temperature. FIGS. 10 yand 1:1 show the gel times and peak temperatures as ya function of the quantity of 20 g. samples of a mixture of polyester styrene soluhydratropaldehyde employed tion with an acid number of 17.2 and a styrene content Example 7. of 33% (same polyester styrene solution as concerned in 120 g. samples of 70% by weight solution of a polyester FIGS. 1-5) were copolymerized in test tubes 20 mm. in obtained from maleic acid, orthophthalic acid -and prodiarneter in an oil bath maintained at 100 C. using 1% pylene glycol 1,2 in a molar proportion of 1:1:2 and and 2% by weight of various phenyl acetaldehyde comhaving an acid number yof 2() in styrene stabilized with pounds according to the invention. FIG. 8 shows the 55 0.01% of hydroquinone were copolymerized at a bath exotherm temperature curves obtained with the samples temperature of 80 C. with phenyl acetaldehyde, benzoyl using 1% of the aldehyde compound. It can be seen from peroxide yand lauroyl peroxide, as well as combinations such curves that hydratropaldehyde is the most active thereof. In addition, plates 10 x 15 cm., 3.5 mm. thick regulator followed by phenyl acetaldehyde, p-methylwere also produced to determine the mechanical properphenyl acetaldehyde and diphenyl acetaldehyde.

The following table gives the gel times, peak temperatures and hardening times observed with the various samples.

ties of the polymeiizates.

The following table gives the gel 'and hardening times observed, as well as the hardness and impact and binding strengths attained.

TABLE "9 Mechanical properties of a plate 3.5 mm. thick after 1 days stor- Gel Hardening age at room temperature Catalyst or regulator Time, time, Min. Min.

Hard- Impact Binding ness Strength, Strength, o/tr kg cnn/ein? kg./em.2

1% Phenylacetaldehyde 21 31 23. 5 13. 8 1, 160 2% Benzoylperoxide 38 44 25. 1 3. 7 1, 370 21%, uroylpeioilrdef 1 22 26 24. 5 6. 2 885 1 ieny ace a e y ep us 1g; gmoylpewxd 11 13 22. 2 5. 5 1, 170 l 0 eny acetal e y e plus 1% Lauroylperoxide i 4 14 22 3 2 1 665 The hardness was measured with a Wolpert-Mikrotestor (diamond pyramide of 136 at 100 g. load).

The impact strength was measured with a Dynstat apparatus No. 573 according to DIN 53 453.

The binding strength was measured With a Dynstat lapparatus No. 573 according to DIN 53 452.

As can be seen from such table the gel and hardening times when using phenyl acetaldehyde were shorter than when double the quantities of the peroxides indicated were used. The impact strength obtained using 1% by Weight of phenyl acetaldehyde Was 122% and 273% higher respectively than when 2% of lauroyl and 2% of benzoyl peroxide were used. While the combinations of phenyl acetaldehyde with the peroxides gave very short gel and hardening times, no noticeable improvement in the mechanical properties were observed.

Example 8 g. samples of the same polyester styrene solution as in Example 5 were copolymerized in test tubes V20 mm. in diameter at a bath temperature of 80 C. with hydratropaldehyde, benzoyl peroxide and a combination of both of these accelerators. As can be seen from FIG. 12 and the following table, results were obtained similar to those in Example 7, namely, shorter gel and hardening times with combined use of the accelerators and high peak temperatures but no improvement in the mechanical properties.

We claim:

1. In a process for the copolymerization of unsaturated polyester resins obtained from polycarboxylic acids and polyhydric alcohols, at least one of which components is ethylenically unsaturated, and liquid ethylenically unsaturated polymerizable monomers with a polymerization regulator, the step which comprises carrying out such copolymerization of the unsaturated polyester resin with the ethylenically unsaturated monomer in contact with a phenyl acetaldehyde compound of the formula wherein Ar is selected from the group consisting of phenyl, alkyl substituted phenyl, alkyloxy substituted phenyl and halogen substituted phenyl and R is selected from the group consisting of hydrogen, alkyl and phenyl as the polymerization regulator.

2. The process of claim 1 in which said phenyl acetaldehyde compound is phenyl acetaldehyde.

3. The process of claim 1 in which said phenyl acetaldehyde is hydratropaldehyde,

4. The process of claim 1 in which said phenyl acetaldehyde compound is diphenyl acetaldehyde.

5. The process of claim 1 in which said phenyl acetaldehyde is p-methylphenyl acetaldehyde.

6. The process of claim 1 in which a combination of hydrotropaldehyde and benzoyl peroxide is used.

TABLE 10 Percent Gel Peak Hardening Catalyst 0r reguutor by wt. M01 Time, Temp., time, Miu.

Min. "C

llydratropaldehyde 2 0. 003 6. 5 94. 5 22 Do 1 0. 0015 10 92 30 1. s 0. 0015 5. 75 19s s. 5 0. s1) 0. 00075 r. 5 194. 5 10. 5

0.0015 09 Ooggm 4.15 181 s 1 15 r Plus Benzoylperoxide 0.15 0.000125 9-75 137 15' Example 9 45 7. The process of claim 1 in which the quantity of 5 parts by Weight of a polyester obtained by heating 1 mol of maleic acid anhydride, 1.6 mol of phthalic anhydride,1.6 mol of ethylene glycol and 1 mol of diethylene glycol were dissolved in l part by Weight of methyl methacrylate at 60 C. and then 20 g. samples thereof copolymerized in test tubes 20 mm. in diameter at a bath temperature of 80 C. causing hydratropaldehyde, benzoyl peroxide and a combination of such accelerators.

As can be seen from the following table the gel times phenyl acetaldehyde compound employed is between 0.1 and 10% by weight of the reaction mixture.

8. The process of claim 1 in which the quantity of phenyl acetaldehyde compound employed is between 0.5 and 3% by Weight of the reaction mixture.

9. The process of claim 1 in which said copolymerization is started at to 120 C.

10. The process of claim 1 in which said copolymerization is started at to 80 C.

11. The process of claim 1 in which a combination of the phenyl acetaldehyde compound and an organic peroxidic polymerization catalyst is used.

References Cited by the Examiner UNITED STATES PATENTS 2,944,994 7/1960 Singleton et al 260-861 2,961,430 11/1960 Davis et al 260-861 FOREIGN PATENTS 603,324 6/ 1948 Great Britain. 735,488 8/ 1955 Great Britain.

MURRAY TILLMAN, Primary Examiner.

LEON I. BERCOVITZ, Examiner, 

1. IN A PROCESS FOR THE COPOLYMERIZATION OF UNSATURATED POLYESTER RESINS OBTAINED FROM POLYCARBOXYLIC ACIDS AND POLYHYDRIC ALCOHOLS, AT LEAST ONE OF WHICH COMPONENTS IS ETHYLENICALLY UNSATURATED, AND LIQUID ETHYLENICALLY UNSATURATED POLYMERIZABLE MONOMERS WITH A POLYMERIZATION REGULATOR, THE STEP WHICH COMPRISES CARRYING OUT SUCH COPOLYMERIZATION OF THE UNSATURATED POLYESTER RESIN WITH THE ETHYLENICALLY UNSATURATED MONOMER IN CONTACT WITH A PHENYL ACETALDEHYDE COMPOUND OF THE FORMULA 